Ash and smoke spewed from Popocatepetl Volcano as seen from Santiago Xalixintla, in the Mexican central state of Puebla, on April 24, 2012. Residents at the foot of Mexico's Popocatepetl volcano no longer sleep soundly since the towering mountain roared back into action over a week ago, spewing out a hail of rocks, steam and ashes. The volcano, Mexico's second highest peak at 5,452 metres, started rumbling and spurting high clouds of ash and steam on April 13, provoking the authorities to raise the alert to level five on a seven-point scale. AFP PHOTO//RONALDO SCHEMIDT (Photo credit should read Ronaldo Schemidt/AFP/Getty Images) (AFP/Getty Images) less

Ash and smoke spewed from Popocatepetl Volcano as seen from Santiago Xalixintla, in the Mexican central state of Puebla, on April 24, 2012. Residents at the foot of Mexico's Popocatepetl volcano no longer sleep ... more

Ash and smoke spewed from Popocatepetl Volcano as seen from... Photo-2938780.42958 - San Antonio Express-News

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Ashes and smoke spew from the Popocatepetl Volcano in Paso de Cortes, in the Mexican central state of Puebla, on April 28, 2012. Residents at the foot of Mexico's Popocatepetl volcano no longer sleep soundly since the towering mountain roared back into action over a week ago, spewing out a hail of rocks, steam and ashes. The volcano, Mexico's second highest peak at 5,452 metres, started rumbling and spurting high clouds of ash and steam on April 13, provoking the authorities to raise the alert to level five on a seven-point scale. AFP PHOTO/Yuri CORTEZ (Photo credit should read YURI CORTEZ/AFP/GettyImages) (AFP/Getty Images) less

Ashes and smoke spew from the Popocatepetl Volcano in Paso de Cortes, in the Mexican central state of Puebla, on April 28, 2012. Residents at the foot of Mexico's Popocatepetl volcano no longer sleep soundly ... more

Ashes and smoke spew from the Popocatepetl Volcano in Paso de... Photo-2938782.42958 - San Antonio Express-News

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Incandescent materials, ash and smoke are spewed from the Popocatepetl Volcano as seen from the Santiago Xalitxintla, in the Mexican central state of Puebla on April 20, 2012. Mexico's Popocatepetl volcano, outside the capital, rumbled continuously and spewed gases and glowing rocks to almost one mile (one kilometer) beyond its crater, authorities said April 20. AFP PHOTO/Yuri CORTEZ (Photo credit should read YURI CORTEZ/AFP/Getty Images) (AFP/Getty Images) less

Incandescent materials, ash and smoke are spewed from the Popocatepetl Volcano as seen from the Santiago Xalitxintla, in the Mexican central state of Puebla on April 20, 2012. Mexico's Popocatepetl volcano, ... more

Big clouds of ash and smoke are spewed from the Popocatepetl Volcano as seen from the Santiago Xalitxintla, in the Mexican central state of Puebla, on April 25, 2012. Residents at the foot of Mexico's Popocatepetl volcano no longer sleep soundly since the towering mountain roared back into action over a week ago, spewing out a hail of rocks, steam and ashes. The volcano, Mexico's second highest peak at 5,452 metres, started rumbling and spurting high clouds of ash and steam on April 13, provoking the authorities to raise the alert to level five on a seven-point scale. AFP PHOTO//RONALDO SCHEMIDT (Photo credit should read Ronaldo Schemidt/AFP/Getty Images) (AFP/Getty Images) less

Big clouds of ash and smoke are spewed from the Popocatepetl Volcano as seen from the Santiago Xalitxintla, in the Mexican central state of Puebla, on April 25, 2012. Residents at the foot of Mexico's ... more

Big clouds of ash and smoke are spewed from the Popocatepetl... Photo-2938784.42958 - San Antonio Express-News

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Taboola Gallery Frame Item-85307.42958 - San Antonio Express-News

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Incandescent materials, ash and smoke are spewed from the Popocatepetl Volcano as seen from the Santiago Xalitxintla, in the Mexican central state of Puebla on April 20, 2012. Mexico's Popocatepetl volcano, outside the capital, rumbled continuously and spewed gases and glowing rocks to almost one mile (one kilometer) beyond its crater, authorities said April 20. AFP PHOTO/Yuri CORTEZ (Photo credit should read YURI CORTEZ/AFP/Getty Images) (AFP/Getty Images) less

Incandescent materials, ash and smoke are spewed from the Popocatepetl Volcano as seen from the Santiago Xalitxintla, in the Mexican central state of Puebla on April 20, 2012. Mexico's Popocatepetl volcano, ... more

Incandescent materials, ash and smoke are spewed from the Popocatepetl Volcano as seen from Santiago Xalitzintla, in the Mexican central state of Puebla, on April 24, 2012. Residents at the foot of Mexico's Popocatepetl volcano no longer sleep soundly since the towering mountain roared back into action over a week ago, spewing out a hail of rocks, steam and ashes. The volcano, Mexico's second highest peak at 5,452 metres, started rumbling and spurting high clouds of ash and steam on April 13, provoking the authorities to raise the alert to level five on a seven-point scale. AFP PHOTO//RONALDO SCHEMIDT (Photo credit should read Ronaldo Schemidt/AFP/Getty Images) (AFP/Getty Images) less

Incandescent materials, ash and smoke are spewed from the Popocatepetl Volcano as seen from Santiago Xalitzintla, in the Mexican central state of Puebla, on April 24, 2012. Residents at the foot of Mexico's ... more

Incandescent materials, ashes and smoke are spewed from the Popocatepetl Volcano in Santiago Xalitzintla, in the Mexican central state of Puebla, on April 26, 2012. Residents at the foot of Mexico's Popocatepetl volcano no longer sleep soundly since the towering mountain roared back into action over a week ago, spewing out a hail of rocks, steam and ashes. The volcano, Mexico's second highest peak at 5,452 metres, started rumbling and spurting high clouds of ash and steam on April 13, provoking the authorities to raise the alert to level five on a seven-point scale. AFP PHOTO/Yuri CORTEZ (Photo credit should read YURI CORTEZ/AFP/GettyImages) (AFP/Getty Images) less

Incandescent materials, ashes and smoke are spewed from the Popocatepetl Volcano in Santiago Xalitzintla, in the Mexican central state of Puebla, on April 26, 2012. Residents at the foot of Mexico's ... more

Ashes and smoke spew from the Popocatepetl Volcano in Paso de Cortes, in the Mexican central state of Puebla, on April 28, 2012. The volcano, Mexico's second highest peak at 5,452 metres, started rumbling and spurting high clouds of ash and steam on April 13, provoking the authorities to raise the alert to level five on a seven-point scale. AFP PHOTO/Yuri CORTEZ (Photo credit should read YURI CORTEZ/AFP/GettyImages) (AFP/Getty Images) less

Ashes and smoke spew from the Popocatepetl Volcano in Paso de Cortes, in the Mexican central state of Puebla, on April 28, 2012. The volcano, Mexico's second highest peak at 5,452 metres, started rumbling and ... more

Ashes and smoke spew from the Popocatepetl Volcano in Paso de... Photo-2938788.42958 - San Antonio Express-News

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Taboola Gallery Frame Item-85307.42958 - San Antonio Express-News

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Ashes and smoke spew from the Popocatepetl Volcano in Paso de Cortes, in the Mexican central state of Puebla, on April 28, 2012. The volcano, Mexico's second highest peak at 5,452 metres, started rumbling and spurting high clouds of ash and steam on April 13, provoking the authorities to raise the alert to level five on a seven-point scale. AFP PHOTO/Yuri CORTEZ (Photo credit should read YURI CORTEZ/AFP/GettyImages) (AFP/Getty Images) less

Ashes and smoke spew from the Popocatepetl Volcano in Paso de Cortes, in the Mexican central state of Puebla, on April 28, 2012. The volcano, Mexico's second highest peak at 5,452 metres, started rumbling and ... more

Ashes and smoke spew from the Popocatepetl Volcano in Paso de... Photo-2938789.42958 - San Antonio Express-News

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An old man walks in a road with the Popocatepetl volcano at the back, in Paso de Cortes, in the Mexican central state of Puebla, on April 28, 2012. The volcano, Mexico's second highest peak at 5,452 metres, started rumbling and spurting high clouds of ash and steam on April 13, provoking the authorities to raise the alert to level five on a seven-point scale. AFP PHOTO/Yuri CORTEZ (Photo credit should read YURI CORTEZ/AFP/GettyImages) (AFP/Getty Images) less

An old man walks in a road with the Popocatepetl volcano at the back, in Paso de Cortes, in the Mexican central state of Puebla, on April 28, 2012. The volcano, Mexico's second highest peak at 5,452 metres, ... more

An old man walks in a road with the Popocatepetl volcano at the... Photo-2938790.42958 - San Antonio Express-News